Olefin-containing streams from refineries often contain butenes-2 and isobutylene in the presence of other four carbon compounds such as butene-1 and n-butane. It is desirable to use parts of such a stream to produce a high octane alkylate gasoline. It is also desirable to separate isobutylene from this mixture, so that the n-butenes can be used to produce valuable 1,3-butadiene. Alternatively, it may be desirable to use a portion of the n-butenes to produce some valuable high purity butene-1.
The presence of isobutylene in a stream to be sent to a butadiene manufacturing process is undesirable since the isobutylene is not useful in the formation of butadiene. Also, to obtain high purity butene-1, the isobutylene must be separated. Isobutylene and butene-1 have very close boiling points, however; and their separation by fractional distillation is very difficult.
The present invention addresses all of these needs and problems and provides a good solution.
It is an object of the present invention to provide a method for producing 1,3-butadiene and a high octane alkylate gasoline from a four carbon olefin-containing stream from refineries. It is also an object to produce high purity butene-1 from such a stream.